Bags of mail have been piling up in the sorting office yard for days as overstretched staff struggle to cope with a new single delivery system, it is said.

Some Holme Valley districts have missed deliveries on some days.

And some of the office's 55 full-time staff are working 80 hours a week in a bid to sort out the mess.

A source, who asked not to be named, said: "Local deliveries are not going out. People are not getting their mail on a regular basis because of a shortage of manpower."

But Royal Mail blamed the problems on a combination of incidents at the sorting office and said it was doing everything to get the service back to normal.

The source claimed: "The system is nearly at a complete meltdown."

The source said Royal Mail was using between six and 10 agency workers a day at Holmfirth, adding: "They are giving them a bag and sending them on their way. One agency worker was told to take out a van loaded with sacks of mail, given an A to Z and told to get on with it.

A spokeswoman for Royal Mail said the Holmfirth office had been hit by unusually high levels of sickness absence coupled with very high volumes of mail.

An electrical fire at the office last Saturday had knocked out power to the building, forcing some sorting and preparation of mail to be moved to another office for safety reasons.

The spokeswoman said: "Inevitably, this led to delays in some mail deliveries in the area and we apologise to customers affected.

"However, we have taken on temporary staff to help clear the backlog and we are doing everything we can to get services back to normal as soon as possible."